(1) Field of the Invention
The present invention pertains to a furnace blower having a co-axially arrange and simplified construction. More specifically, the furnace blower comprises an electric motor press-fit into a cylindrical blower housing and a nozzle that is also press-fit into the blower housing. The motor has a shaft with a fan mounted on the shaft and positioned in the nozzle. The press-fit assembly of the motor into the blower housing as well as the nozzle into the blower housing simplifies the construction of the furnace blower and reduces its manufacturing costs. The furnace blower is also smaller than prior art furnace blowers which enables it to be readily retrofit into conventional furnaces in place of the prior art furnace blower.
(2) Description of the Related Art
A prior art furnace blower 10 is shown in FIGS. 1 and 2. Prior art furnace blowers, and in particular oil burner furnace blowers typically include an electric motor 12 mounted to the side of a fan housing 14 that encloses a squirrel cage fan (not shown). The fan housing 14 also supports an oil pump 16 of the furnace and a blower nozzle 18 that directs a flow of air generated by the squirrel cage fan into the combustion chamber of the furnace.
The fan housing of these prior art furnace blowers is constructed of two housing sections 22, 24 that are cast of metal. With the housing sections being cast, it is necessary to machine surfaces on the exterior of the housing sections to provide flat, smooth surfaces to which the motor 12, the oil pump 16 and the blower nozzle 18 can be mounted. The two housing sections 22, 24 are also machined to provide flat, smooth surfaces where they are joined together. It is also necessary to machine interior surfaces of the cast housing sections that receive axially aligned bearings (not shown) that support the shaft of the squirrel cage fan. The machining steps required of the fan housing sections significantly contribute to the overall cost of manufacturing the furnace blower.
In addition, the motor, oil pump and blower nozzle are secured to the fan housing sections by fasteners, for example, threaded screws and bolts. Assembling these component parts to the housing sections with the threaded fasteners contributes significantly to the time required to assemble the furnace blower and thereby also increases the assembly""s cost of manufacture.
What is needed to overcome the disadvantages of the prior art furnace blower constructions is an improved construction of a furnace blower that reduces the number of component parts of the blower and simplifies its assembly. The furnace blower of the invention provides these advantages.
The furnace blower of the invention is contained in a cylindrical housing having inlet and outlet ends at axially opposite ends of the housing. The shell of the electric motor employed in the blower is formed of extruded aluminum and has three radially projecting fins. The radially projecting fins are press-fit into the interior of the cylindrical blower housing and center the electric motor coaxially in the housing with a radial spacing between the motor shell and the interior surface of the housing. The radial spacing allows a flow of air through the inlet end of the housing and around the motor as the motor is operated, thereby cooling the motor. A shaft of the motor projects into the motor housing and a fan is mounted on the shaft. The fan is not a squirrel cage fan as employed in prior art blowers, but a fan with radially projecting blades.
A combustion tube is also coaxially press fit into the interior of the blower housing. The combustion tube has an inlet opening and an axially opposite outlet opening and tapers as its extends between its inlet and outlet openings. In the preferred embodiment the combustion tube tapers through a curve as it extends from its inlet opening to its outlet opening. The inlet opening of the combustion tube is press fit into the interior of the cylindrical housing. The cylindrical housing has a circular end wall at its outlet end and the end wall has a circular opening that engages around an intermediate portion of the combustion tube and provides further support to the combustion tube in the housing.
The construction of the furnace blower of the invention is smaller than that of prior art furnace blowers which enables the furnace blower to be retrofit into most exiting furnaces. The combustion tube outlet end is dimensioned the same size as prior art furnace blowers which also facilitates retrofitting the furnace blower of the invention to existing furnaces. The simplified press fit construction of the furnace blower reduces the number of its component parts and the time required for its manufacture, thus significantly reducing its cost of manufacture from that of prior art furnace blowers.